Formation-sampling apparatus



United States Patent [72] Inventor Frank R. Whitten Houston, Texas [21]Appl. No. 812,726 [22] Filed April 2, 1969 [45] Patented Sept. 29, 1970[73] Assignee Schlumberger Technology Corporation New York, New York acorporation of Texas [54] FORMATION-SAMPLING APPARATUS 33 Claims, 11Drawing Figs.

[52] [1.5. CI. 166/100, 166/55.l [5i] lnt.Cl E2lb 49/00 [50] Field ofSearch 166/ 100, 55.1; 175/452 [56] References Cited UNITED STATESPATENTS 2,612,346 9/ 1952 Nelson 166/ l00X 2,903,068 9/ 1959 Lebourg166/ 100x 3,295,615 1/1967 Brieger et a1. 166/ l 00X 3,352,361 11/1967Urbanosky 3,385,364 5/1968 Whitten Primary Examiner- David H. BrownAttorneysErnest R. Archambeau, 1%., William J. Beard,

Donald H. Fidler, David L. Moseley, Edward M. Roney and William R.Sherman ABSTRACT: In each of the several embodiments of the new andimproved fluid-sampling apparatus disclosed herein, sample-admittingmeans adapted to be selectively extended therefrom include an annularsealing pad operatively arranged around the forward end of a tubularsampling member so that, upon contacting a well bore surface, the padwill make firm sealing engagement therewith. Means are provided fordelaying the establishment of flow communication between asampie-collecting system in the apparatus and an earth formation beingtested until the sample-admitting means have been extended. Means areuniquely arranged in the sampling member for regulating the flow offluid samples as well as for limiting the entrance of mudcake andunconsolidated formationmaterials that might otherwise plug the samplingapparatus or disrupt the sealing engagement of the sealing pad.

Patented Sept. 29, 1910 I V 3,530,933

Sheet I. of '7 Frcznk Whitten KINVENTOR f A TQRNEY 25 s. 24 mi PatentedSe t. 29,1970 3,530,933

Sheet 2 of? Fmbk 'RuWhi'tten INVENTOR ATIORNE'Y Patented Sept. 29,19703,530,933

Sheet 3 of? FIG. 4

Frank R. Whitten INVENTOR ATTORNEY v Patented Sept. 29,1970 I :i3 530,933

Sheet of! w mi:

4a Frd-nik R Whitteh INVENTOR mm a j ATTORNEY Patented Sept. 29, 19703,530,933

Sheet, of 7' FIG. 6

Frqhk R. Whitten 'INVENTOR f .EYATYTORNEY Patented Sept. 29, 1970 I3,530,933

Sheet 6 of 7 Ran R, Whitten 1 INVENTOR' ATTORNEY Patented Sept. 29',1970 '2 3,530,933

Sheet Y of 7 FIG. 9

Fra hk R. Whitten v {NVENTOR A'rTbRA/Ey I FORMATION-SAMPLING APPARATUSAlthough the new and improved fluid-sampling tools disclosed in U.S.Pat. No. 3,385,364 have generally been highly successful, there havenevertheless been occasions where at least one of the several testingunits on such a too] did not effect satisfactory fluid communicationwith an earth formation to obtain a fluid sample therefrom. For example,in some instances, one or more of the wall-engaging sealing pads onthese tools may not make a satisfactory sealing engagement with theborehole wall where the formations being investigated are relativelyunconsolidated. The problem here is attributed to the inability of thepad members to remain in sealing engagement with the borehole wall sincesuch unconsolidated formation materials will tend to be rapidly erodedaway from under the face of the pad as a fluid sample is beingwithdrawn.

To reduce the rate at which these unconsolidated formation materials arewashed away, these aforementioned fluid-sampling tools have beenarranged to regulate the flow rate at which fluid samples are admitted.In one manner of accomplishing this, a slidable piston is operativelyarranged within the sample-receiving chamber of each testing unit toslowly displace a quantity of water contained therein through an orificeinto an adjacent atmospheric chamber as the pressured fluid sample isadmitted into the sample chamber on the opposite side of the piston.

Although this and other measures have improved the odds of obtainingfluid samples from unconsolidated formations, there are still someproblems arising in the use of such apparatus. For example, where theflow rate at which a sample is obtained must be greatly limited, thefluid-sampling apparatus often must be held in position for perhaps anhour. Such long waits generally make it necessary to continuallyreciprocate the suspension cable to prevent it from becoming stuck inthe well as by differential sticking or key-seating. Moreover, extendedtesting cycles will expend valuable rig time as well as reduce thenumber of operations that can be conducted during an allotted time. Itwill also be recognized that the overall length of each testing unitmust be increased simply to accommodate the volume of water or so-callcdwater cushion" carried in the sample chamber.

Accordingly, it is an object of the present invention to provide new andimproved fluid-sampling apparatus operatively arranged for reliablyeffecting fluid communication with various types of borehole surfacesand formation materials.

Another object of the present invention is to provide new and improvedfluid-sampling apparatus that is capable of taking fluid samples atrapid flow rates without disrupting fluid communication with theformation.

Still another object of the present invention is to provide new andimproved fluid-sampling apparatus that does not necessarily require aspace-consuming water cushion in its sample-receiving chamber.

These and other objects of the present invention are attained by new andimproved fluid-sampling apparatus having sample-admitting meansincluding a tubular sampling member adapted to be placed into fluidcommunication with a selected surface of a well bore such as a boreholewall. To assure reliable fluid communication of the tubular member withthe borehole wall, packing means are operatively mounted around thetubular member and adapted to sealingly engage the borehole wall forisolating the selected surface. The sampleadmitting means furtherinclude means for limiting the entrance of unconsolidated formationparticles as well as mudcake from the borehole wall or other unwanteddebris or fluent matter that might otherwise tend to impede or halt thefluid-sampling operation.

The novel features of the present invention are set forth withparticularity in the appended claims. The invention, together withfurther objects and advantages thereof, may be best understood by way ofthe following exemplary apparatus employing the principles of theinvention as illustrated in the accompanying drawings, in which:

FIG. 1 depicts fluid-sampling apparatus of the present invention as itmight appear within a borehole; v

FIG. 2 is a somewhat schematic representation of one preferredembodiment of the apparatus depicted in FIG. 1;

FIGS. 3-5 are views similar to FIG. 2 depicting the apparatus atselected sequential stages of a typical testing operation; a

FIG. 6 depicts an alternative embodiment of fluid-sampling apparatusalso employing the principles of the present invention;

FIGS. 7 and 8 are'partial views similar to FIGS. 3 and 4 butrespectively illustrate the progressive positions of various elements ofthe preferred embodiment shown in FIG. 6 during the course of a typicalsampling operation;

FIG. 9 illustrates still another embodiment of fluid-sampling apparatusarranged in accordance with the present invention;

FIG. 10 illustrates the embodiment of FIG. 9 during a typical samplingoperation; and

FIG. 11 shows an alternative arrangement for obtaining an increasedrange of lateral extension for any of the various embodiments of thesample-admitting means respectively depicted in FIGS. 2, 6 and 9.

Turning now to FIG. 1, fluid-sampling apparatus 20 incorporating theprinciples of the present invention isshown suspended from amulti-conductor cable 21 in a well bore such as a borehole 22 containinga well control fluid. The apparatus 20 has been positioned adjacent aparticular formation interval 23 for collecting a sample of produciblefluids from that formation. The cable 21 is spooled in the usual mannerfrom a winch 24 at the earth s surface, with some ofits conductors beingconnected to a switch 25 for selective connection to a power source 26and others being connected to typical indicating and recording apparatus27. To permita number of tests to be made during a single trip into theborehole 22, the fluid-sampling apparatus 20 is comprised of acorresponding number of tandemly-arranged sampling units, as at 28, thatare each capable of independent operation and respectively includeextendible sample-admitting means-.29 (or 100 and 200) spatiallydisposed along one side of the sampling apparatus. As illustrated inFIG. 1, one of the sample-admitting means 29 (or 100 and 200) has beenextended into fluid communication with the exposed face of the formation23 for obtaining a sample of connate fluids therefrom.

. As illustrated schematically in FIGS. 2-5, each testing unit 28 of thefluid-sampling apparatus 20 is basically comprised of theselectively-extendible sample-admitting means 29 for obtaining samplesof formation fluids, sample-collecting means 30 for recovering suchsamples, and selectively-operable means 31 for retracting thesample-admitting means. To operate these several means 29-31, a numberof selectivelyoperable, normally-closed valves 32-36 areoperativelyarranged for selectively admitting well control fluids fromthe borehole 22 to their respectively associated pressure-responsivemeans to utilize the hydrostatic pressure of the boreholefluids as asource of motivating power.

Generally speaking, the several means 3036 of the apparatus of thepresent invention are arranged similarly to their respectivecounterparts shown in US. Pat. No. 3,385,364 to employ the hydrostaticpressure of the fluids in the borehole 22 for operation of the apparatus20. Thus, as will subsequently be described, the valves 32-36 arenormally closed; and as the valves are successively opened in responseto electrical signals from the surface, the well control fluids areselectively directed to the particular pressure-responsive means 29 (orand 200) as well as 30 and 31 that each valve is controlling.Accordingly, these several means 30-36 are illustrated onlyschematically in the drawings and need to be described only as isnecessary to understand their functions in the new and improved tool 20of the present invention.

The sample-collecting means 30 include a sample receiver which, asillustrated, may in some circumstances be divided into upper and lowerchambers 37 and 38 separated from one another by a partition 39 having aflow restriction or orifice 40,

therein. When these dual chambers 37 and 38 and interconnecting orifice40 are employed, a liquid cushion 41 (such as water) is initiallydisposed in the lower chamber 38 and isolated therein by a floatingpiston 42. Since the upper chamber 37 is initially empty and at a low oratmospheric pressure, formation fluids (at whatever the formationpressure is) entering the sample chamber 38 will move the piston 42toward the partition 39 at a rate regulated by the discharge of thewater cushion 41 through the orifice 40. As previously discussed,however, elimination of the water cushion 41 will reduce the overalllength of each testing unit 28. Thus, as will subsequently beappreciated, the success of the present invention does not depend uponthe water cushion 41 and it has been illustrated here only to show thatit may be used, if desired, with the new and improved formation-samplingapparatus of the present invention.

To conduct fluid samples from the sample-admitting means 29 (or 100 and200) to the sample-collecting means 30, passage means are included suchas a fluid passage 43 in the body 44 of the apparatus 20 that isserially divided by a pair of pressure-actuated valves 45 and 46operatively arranged so that the first valve 45 is selectively opened toadmit a fluid sample to the sample chamber 38 and the second valve 46 isselectively closed to trap the sample therein. A pressure transducer 47is connected to an intermediate portion of the passage 43 between thevalves 45 and 46 and adapted to provide representative signals that aretransmitted through the cable 21 to the indicating and recordingapparatus 27 at the surface.

As fully described in the aforementioned patent, the retracting means 31are comprised of one or more pressure-developing pistons 48 operativelyarranged in a hydraulic chamber 49 that is coupled by way of an outletpassage 50 and a normally closed pressure-actuated valve 51 to anemergency release apparatus 52 and the sample-admitting means 29 (or 100and 200). As will be later explained, whenever the hydraulic valve 51 isopened, a pressured hydraulic fluid is operatively employed forretracting the sample-admitting means 29 (or 100 and 200). It will beunderstood, of course, that so long as the hydraulic valve 51 remainsclosed, the hydraulic pressure developed by the pressure-developingpistons 48 will be inoperative. To actuate the hydraulic valve 51, one,or preferably two, control valves, as at 35 and 36, are arranged forselective operation in response to signals from the surface. Byarranging the control valves 35 and 36 in parallel, should one valvefail to open, the other control valve will provide a second opportunityfor opening the hydraulic valve 51.

Should some malfunction in the retracting means 31 prevent theretraction of the sample-admitting means 29 (or 100 and 200), theemergency release apparatus 52 is arranged to selectively admit theborehole fluids into the apparatus 20 for equalizing the pressuredifferential across the sample-admitting means. As described in US Pat.No. 3,385,364, the emergency release apparatus 52 is associated with anextendible wall-engaging piston member 53 that (upon opening ofthecontrol valve 34) is adapted to displace the tool body 44 away from onewall of the borehole 22 as the sample-admitting means 29 (or 100 and200) are beingextended in the opposite direction toward the other wallof the borehole. Ordinarily upon opening of the hydraulic valve 51, thewall-engaging piston 53 will be retracted along with thesample-admitting means 29 (or 100 and 200). However, should there besome malfunction, borehole fluids will be admitted into the passage 50once the outer end of the extendible wall-engaging member 53 is brokento open an enclosed axial passage 54 therein.

In the sample-admitting means 29 shown in FIG. 2, an elongated tubularmember 55 is slidably disposed for longitudinal movement within alateral bore 56 formed in the body 44 of the testing unit 28 and fluidlysealed in relation thereto as by an O-ring 57 coaxially mounted aroundthe forward portion of the lateral bore. The sample-admitting means 29further include an inner tubular member 58 that is coaxially disposedwithin the outer tubular member 55 and adapted for longitudinal movementtherein from the retracted or rearward position depicted in FIG. 2 to anextended or forward position (FIG. 4) for securing fluid samples. Theinner fluid-sampling member 58 is fluidly sealed in relation to theouter tubular member 55 as by an O-ring 59 mounted around anenlargeddiameter shoulder 60 on the rear portion of the inner member andan O-ring 61 arranged within the forward portion of the outer member,with these longitudinally-spaced O-rings defining an elongated annularspace 62 between these tubular members that is at atmospheric pressure.

In the preferred arrangement of the sample-admitting means 29, therearward end of the outer tubular member 55 carries a tubular body 63that is fluidly sealed therein, as by an O-ring 64. To secure thetubular body 63 against rearward and forward movement in relation to theouter member 55, as shown generally at 65, the rearward end of thetubular body is slightly enlarged and secured within a complementarycounterbore formed in the rearward end of the outer tubular member by asnap ring. For reasons that will subsequently become apparent, a thirdand still smaller elongated tubular member 66 having a reduced-diameteror spooled intermediate portion between longitudinally-spaced enlargeddiameter shoulders 67 and 68 thereon is slidably telescoped within thecoincidentally-aligned axial bores 69 and 70 of the inner tubular member58 and tubular body 63.

The innermost tubular member 66 is arranged so that in its initialposition, its longitudinally-spaced shoulders 67 and 68 are respectivelypositioned within the axial bores 69 and 70 and fluidly sealed inrelation to the inner tubular member 58 and tubular body 63 as byO-rings 71 and 72. The forward end of the slidable tubular member 66 isclosed as by a transverse wall 73; and the rearward portion of thistubular member is extended through the rear of the tubular body 63 andfluidly sealed in relation thereto as by an O-ring 74. The innermostmember 66 is secured against forward movement in relation to the othertubular members 55 and 58 as by an outwardly directed shoulder or flange75 thereon which is normally abutted against the rear face of thetubular body 63. To provide fluid communication between the axial bore69 of the tubular sampling member 58 and the axial bore 76 of theinnermost tubular member 66, the forward portion of the innermost memberis slotted or drilled, as at 77, ahead of its forward enlarged shoulder67 and these apertures are covered with a suitable filtering member suchas a meshed screen 78 or other porous material.

To selectively extend the sample-admitting means 29, piston means, suchas an enlarged annular piston member 79 having a tubular forwardextension, are slidably disposed in an enlarged annular bore 80 formedcoaxially in the tool body 44 around the lateral bore 56 and coupled, asat 81, to the forward end of the outer tubular member 55. O-rings, as at82 and 83, are appropriately arranged around and within the pistonmember 79 for fluidly sealing the piston member within the enlargedcoaxial bore 80; and an O-ring 84 is coaxially mounted around theforward end of the enlarged bore for fluidly sealing the tubularextension of the piston in relation to the tool body 44 and defining anenclosed annular space 85 ahead of the piston that is initially atatmospheric pressure. Accordingly, it will be appreciated that uponintroduction of borehole fluids through a passage 86 into the rear ofthe enlarged annular bore 80 behind the piston member 79, thesample-admitting means 29 will be urged forwardly in relation to thetool body 44 and toward an adjacent wall of the borehole 22.

Sealing means, such as an annular elastomeric sealing pad 87 arranged onthe front ofa rigid backing plate 88, are operatively mounted on theforward end of the outer tubular member 55 and adapted to be movedthereby into sealing engagement with a borehole wall. To enable thesealing pad 87 to better conform to the contour of an irregular boreholewall, the rigid backup plate 88 is movably and sealingly coupled to aspherically-shaped enlarged head 89 on the forward end of the outertubular member 55. Thus, upon forward movement of the sample-admittingmeans 29, the sealing pad 87 will be free to swivel in relation to theenlarged head 89 and assume a position where the forward face of the padis at least substantially parallel to the particular surface of theborehole wall it is contacting. Once the elastomeric pad 87 is urgedagainst a borehole wall, the substantial forces urging it into sealingengagement therewith will isolate the adjacent surface of the wall andthe central opening 90 through the pad from the borehole fluids.

To obtain a fluid sample from a selected formation, theformation-sampling apparatus is positioned as shown in FIG. 1 in theborehole 22 opposite the formation 23. At this point, however, thevarious elements of the apparatus 20 will still be in their initialpositions substantially as shown in FIG. 2. Then (as best seen in FIG.3), once the apparatus 20 is in position, the control valve 34 isselectively opened to admit well control fluids into the body passages86 and 91 for simultaneously extending the piston 79 and the extendiblewall-engaging member 53 in opposite lateral directions. Once the outerend of the extendible wall-engaging member 53 (or, perhaps, the rearface of the apparatus 20) engages the rear wall of the borehole 22,continued forward movement of the piston member 79 will firmly urge thesealing member 87 into sealing engagement against the adjacent surfaceof the borehole with a substantial force that is equal to thehydrostatic pressure of the well control fluids multiplied by thecross-sectional area of the piston 79 through O-rings 82 and 84. Aspreviously mentioned, the swivel connection 89 allows the sealing member87 to assume an effective position in relation to the configuration ofthe borehole wall.

It will, of course, be appreciated that the extension of the piston 79will initially advance the telescoped tubular members 55, 58 and 66simultaneously. However, as will subsequently be discussed, thesample-admitting means 29 are operatively arranged to delay forwardmovement of the inner tubular member 58 in relation to the outer tubularmember 55 until the sealing member 87 has been extended for establishingsealing engagement with the borehole wall. To accomplish thisselectively delayed but positive extension of the inner sampling member58 in relation to the outer sampling member 55, the sample-admittingmeans 29 are so arranged that as long as the outer member is fullyretracted within the housing bore 56, the flanged end 75 of theinnermost member 66 is against the rear wall of the housing bore andcannot be shifted rearwardly in relation to the inner and outer membersby the hydrostatic pressure acting rearwardly on the effective areadefined between the O-rings 71 and 74. Moreover, so long as the O-ring71 on the forward shoulder 67 of the innermost tubular member 66 issealingly engaged within the axial bore 69 of the inner sampling member58, the hydrostatic pressure of the borehole fluids will be actingrearwardly on the inner member to urge it against the forward face ofthe tubular body 63.

Accordingly, the inner sampling member 58 is prevented from movingforwardly until the piston 79 is extended for placing thesample-admitting means 29 into fluid communication with the formation23. Once, however, the sample-admitting means 29 move forwardly and therear flange 75 of the slidable tubular member 66 is displaced from therear wall of the-housing bore 56, the rearwardly-acting pressure forceson the slidable member will begin urging it rearwardly in relation tothe advancing tubular members 55 and 58 and the tubular body 63. Itwill,'therefore, be recognized that once the innermost tubular member 66moves sufficiently rearwardly in relation to the outer and inner tubularmembers 55 and 58 so as to withdraw the O-ring 71 from sealingengagement within the inner bore 69 of the inner tubular member 58, theintermediate spooled portion of the innermost member functions (inconjunction with the members 58 and 63) as a valve for selectivelyadmitting borehole fluids into the previouslyclosed annular space 92between the O-rings 59 and 64 and the O-rings 71 and 72. Once theborehole fluids enter this space 92, their hydrostatic pressure will,thereafter, be urging the inner tubular member 58 forwardly in relationto the outer tubular member 55 with a substantial force since theannular bore space 62 between the O-rings 59 and 61 is at atmosphericpressure.

Accordingly, as previously mentioned, the sample-admitting means 29 ofthe present invention further include means for selectively delayingthis forward movement of the inner tubular member 58 so as to enable thesealing member 87 to first be sealingly disposed against the boreholewall before the inner tubular member is extended. In the preferredmanner of accomplishing this, the annular space 93 (FIG. 2) defined inthe axial bore 70 of the tubular body 63 and between the O-rings 72 and74 is initially filled with a viscous fluid or some suitable fluentmaterial such as a silicone grease or other deformable plasticmaterials, and a small flow passage 94 (H6. 3) is formed in the shoulder68 for bypassing the O- ring 72 to provide restricted communicationbetween this fluid-filled annular space and the space 95 around thespooled portion of the member 66 defined between the O-rings 71 and 72.Thus, the time required for the innermost tubular member 66 to shiftrearwardly from its initial position (FIG. 2). to its final position(FIG. 3) will be governed by the time required for the effective forceof the hydrostatic pressure acting rearwardly on the tubular member 66to displace the viscous fluid from the space 93, through the restrictedpassage 94, and into the atmospheric space 95.

It will, of course, be understood that even upon application of asubstantial forwardly directed pressure force on the piston portion 60of the sampling tube 58 as illustrated in FIG. 3, the forward end of thetubular sampling member can penetrate the adjacent formation (as at 23)only so far as is permitted by the nature of the particular formationmaterials. Thus, should the formation 23 be fairly competent, theforward end of the tube 58 will, most likely, still be incapable ofmaking a significant penetration into the formation. Thus, it ispresumed that, at best, this forwardly acting pressure force willprobably cause the forward end of the sampling tube 58 to penetrate onlythe so-called mudcake(as at 96) that typically lines the wall of aborehole traversing a potentially-producible earth.

formation, as at 23.

As depicted in FIG. 3, forward movement of the piston 79 upon opening ofthe control valve 34 will, therefore, successively extend and compressthe sealing member 87 into sealing engagement with the mudcake-linedface of the formation 23 and then drive the tubular sampling member 58forwardly through the now isolated central opening 90 into the mudcakeAccordingly, in keeping with the objects of the invention, as-

the forward end of the sampling tube 58 penetrates the mudcake (as at96) on the borehole wall, the resulting cylindrical plug of mudcakedriven into the nose of the tube will be forcibly driven (by formationpressure) rearwardly into the enlarged annular space 92 to the rear ofthe piston 60 and around the rearward portion of the filtering screen78.-

Similarly, should the tube 58 penetrate an unconsolidated producibleformation, any formation particles carried into the sample-admittingmeans 29 by the flow of connate fluids will; also be received within themomentarily-voided annular space 92. Ultimately, however, formationfluids as well as the mudcake plug (and possibly at least some loosenedformation particles) will have filled the voided annular space 92 toequalize the momentary pressure differential created by the initialforward movement of the sample-admitting means 29. Thus,

once the initial forward movement of the sampling tube 58' is halted,any plug of the mudcake 96 that would otherwise have portion of thelateral blocked either the inner bore 69 of the sampling tube or thefiltering screen 78 will be safely disposed in the annular space 92 tothe rear of the screen. Similarly, should there also be any formationmaterials displaced after the plug of mudcake is removed, these too willbe disposed behind the mudcake plug in the forward portion of theannular space 92. Although the displaced mudcake plug and perhaps some,if any, of such initially displaced formation materials will be ratherimpermeable, at least a substantial portion of the forward end of thescreen 78 will be free of foreign matter so as to not materially impedethe subsequent flow of formation fluids through the filtering screen. Itwill be appreciated, of course, that the screen 78 is selectively sizedto strain out such loosened formation particles. It should also berecognized that the selectively limited volume of the momentarily voidedspace 92 will be correspondingly related to the forward travel of thesampling tube 58. Thus, the forward position of the sampling tube 58illustrated in FIG. 3 will be determined by the quantity of displacedmudcake and formation particles.

Accordingly, at this point in the operating cycle of the tool 20, thesample-admitting means 29 will have established fluid communication withthe formation, as at 23, being tested before a fluid sample is taken. Byselectively displacing the plug of mudcake as well as any formationparticles that may initially enter the sample-admitting means 29 intothe rearward space 92, at least a substantial portion of the filteringscreen 78 will be available for straining fluid samples upon opening ofthe flow line valve 45. Thus, as seen in FIG. 4, a formation fluidsample is obtained by simply opening the flow line valve 45; and then,once the transducer 47 indicates that the sample chamber 38 is filled,closing the seal valve 46.

Once the flow line valve 45 is opened, there will be a substantialpressure differential between the formation pressure and the low oratmospheric pressure in the upper chamber 37 that will promote flow ofthe connate fluids into the sampleadmitting means 29 at a regulated rateas, for example, might be determined by the orifice 40. If, for example,the formation 23 is fairly competent, there will be little or no erosionof the formation materials and the sampling tube 58 will remain in aboutthe same relative position shown in FIG. 3. On the other hand, shouldthe formation 23 be unconsolidated, it will be recognized that unlessthe space 92 were previously filled, the connate fluids will again carrya selectively limited quantity of formation particles into the samplingtube 58 once the flow line valve 45 is opened.

Accordingly, as illustrated in FIG. 4, these loosened formationparticles will rapidly fill the volume remaining in the selectivelylimited annular space 92 as the connate fluids pass on through thefiltering screen 78 and into the sample chamber 38. At the same time, asthese loosened particles move into the sampling tube 58, the formationpressure acting forwardly on the piston member 60 will simultaneouslyadvance the sampling tube a corresponding distance into the formation23. The limited volume of the annular space 92 and inner bore 69 of thesampling tube 58 will, however, be quickly filled with a packed columnof the loosened particles. Once this occurs, it will be appreciated thatno further movement of loosened formation materials can take place sincethe packed column will be fully supported within the sample-admittingmeans 29. Thereafter, only connate fluids can flow into thesample-admitting means 29 with this packed column of formation materialsserving as a filtering media that is well supported by the screen 78. Itwill be recognized, therefore, that once the erosion of formationmaterials is halted, the sealing member 87 will be capable of retainingeffective sealing engagement against the borehole wall for the entiretesting operation.

As best seen in FIG. 5, to retrieve the fluid-sampling apparatus 20, thecontrol valve 35 (or 36) is actuated to open the normally closedhydraulic valve 51. By opening the valve 51, the high-pressure hydraulicfluid is admitted through the passage 50 into the enclosed annularspaces 85 and 97 (ahead of the pistons 79 and 53) that were initially atatmospheric pressure. Since the hydraulic pressure is greater than thehydrostatic pressure of the borehole fluids, as the hydraulic fluidenters these spaces and 97, the piston 79 and extendible member 53 arenormally returned to their initial positions. Once these members 53 and79 have been returned, the fluidsampling apparatus 20 can, of course, beeither retrieved from the borehole 22 or repositioned therein. 1

It should be noted that the sampling tube 58 is not retracted when theouter tubular member 55 is restored to its original retracted position.Thus, for purposes of economy and safety, means must be provided forallowing the protruding portion of the sampling tube 58 to either bendreadily or break off as the formation-sampling apparatus 20 is beingmoved through the borehole 22. This can, of course, be convenientlyaccomplished by either selectively weakening the forward portion of thesampling member 58 or else arranging the tube to bend easily underlateral loading.

In some instances, however, it will be recognized that the differentialbetween the hydrostatic and formation pressures may be sufficient tohold the sealing member 87 firmly compressed against the formation 23.Accordingly, to prevent this, an equalizing valve 98 is arranged as seenin FIGS. 4 and 5 in such a manner that once the hydraulic valve 5 I isopened, the pressured hydraulic fluid will also open the equalizingvalve to equalize pressures across the sample-admitting means 29 (or and200) and facilitate disengagement of the sealing member 87 from theformation wall. When the valve 98 is in its normally-closed position (asseen in FIG. 4), the hydrostatic pressure of the borehole fluids willhold it closed so long as the hydraulic valve 51 is closed. As best seenin FIG. 5, therefore, opening of the hydraulic valve 51 will move thevalve member 98 outwardly to admit the borehole fluids into the lateralhousing bore 56.

Should there be some malfunction in the retracting system 31, as, forexample, sticking of the hydraulic valve 51, the fluid-samplingapparatus 20 can still nevertheless be retrieved by the emergencyrelease apparatus 52. Thus, should the necessity arise, the outer end ofthe extendible wall-engaging member 53 can be quite simply broken bypicking up on the apparatus 20. Then, once the outer end ofthe axialpassage 54 is opened, the borehole fluids will be admitted into thespaces 85 and 97.

Referring again to FIG. 3, it will be appreciated that during thisportion of the operating cycle, there may be a momentary, but stillsubstantial, pressure differential between the borehole fluids and theforward open end of the sampling tube 58. Thus, although the mudcakelayer 96 (and/or the contiguous surface of the formation 23 as well) maygenerally be sufficiently competent to prevent channeling of theborehole fluids around the forward face of the packing element 87 andinto the forward end of the sampling tube 58, there is nevertheless adistinct risk that such channeling could occur.

It will also be recognized that when the sample-admitting means 29 arein the position shown in FIG. 3, there will be a substantial pressuredifferential existing across the filtering screen 78 until the pressurein the housing bore 56 and flow line 43 rise to the formation pressure.Thus, even though the voided space 92 behind the piston member 60 willreceive at least a portion of whatever materials are pulled off of theborehole wall, a significant quantity of the plug of mudcake 96 couldalso coat part ofthe screen 78.

Accordingly, to eliminate such undesirable coating of the screen 78 andchanneling of borehole fluids through the mudcake 96 around the forwardface of the elastomeric sealing members of the fluid-sampling apparatus20, the present invention also includes an alternative embodiment I00 ofsample-admitting means to be used with this apparatus. Since the balanceof the sampling apparatus 20 is preferably arranged in the same mannerwith either the sample-admitting means 29 or the sample-admitting means100, no change has been made in those reference numerals designating theunchanged elements of the formation-sampling apparatus of the presentinvention.

I Turning now to FIG. 6, the sample-admitting means 100 are shown in aninitial position corresponding to the retracted position of thesample-admitting means 29 as depicted in FIG. 2. Similar to thesample-admitting means 29, the sample-admitting means 100 include innerand outer telescoped tubular members 101 and 102, with the outer memberbeing slidably disposed in the lateral bore 56 of the tool body 44 andits forward end fluidly sealed within the O-ring 57. An annularelastomeric sealing member 103 is carried on a rigid support plate 104that is mounted for limited swiveling movement on a spherically-shapedhead 105 on the forward end of the outer tubular member 102. Toselectively extend the sample-admitting means 100, an annular piston 106is fluidly sealed, as by O-rings 107 and 108, within the coaxial annularbore 80 in the body 44, and the piston includes a tubular forwardextension 109 that is sealingly extended through the O-ring 84 andconnected to the spherical head 105.

The inner member 101 is generally arranged in a similar fashion to thesampling tube 58 and includes an enlarged piston head 110 on itsrearward end that is sealingly engaged, as by an O-ring 111, within theforward portion of the axial bore 112 of the outer tubular member 102.An O-ring 113 is arranged within the spherical head 105 for sealingengagement around the forward portion of the sampling tube and definesan enclosed annular space 114 at atmospheric pres sure between the tubes101' and 102 ahead of the piston member 110.

A tubular body 115 is coaxially mounted in the rearward portion of theaxial bore 112 of the outer tubular member 102 and secured againstlongitudinal movement therein as at 116. Enlarged-diameter shoulders 117and 118 on the forward and rearward ends of the tubular body are fluidlysealed by O-rings 11,9 and 120 within the outer tubular member to definean enclosed annular space 121 between the O-rings and the tubularmembers 102 and 115 that is initially at atmospheric pressure.

in its preferred form, the forward portion of the tubular body 115iscounterbored, as at 122, and a restricted lateral passage 123 isarranged through the wall of the body for communicating the rear of thecounterbore with the annular space 121.

An elongated valve member such as a cylindrical body 124 is slidablydisposed in the tubular body 115 and provided with a pair of closelyspaced O-rings 125 and 126 on its rear portion sealingly engaged withinthe reduced bore at the rear of the tubular body. An enlarged-diametershoulder 127 near the forward end of the cylindrical body 124 carries anexternal ring 128 that is sealingly received within the counterbore 122at the forward end of the tubular body 115. An axial bore 129 extendingrearwardly from the forward end of the cylindrical body 124 isterminated at a lateral passage 130 through the wall of the body betweenthe spaced O-rings 125 and 126 thereon. A tubular extension 131 from theforward end of the cylindrical body 124 and in coincidental alignmentwith the axial bore 129 is covered with a suitable filtering member orfinely meshed screen 132 that covers a plurality of small apertures orlateral holes 133 in the tubular extension. The forward end of thetubular extension 131 is preferably closed by a transverse plug 134.

7 It will, of course, be recognized that with the sample-admitting means100 in the illustrated retracted position, the cylindrical body 124cannot move rearwardly; and the rearwardmost flanged end 135 of the bodyprevents the cylindrical body from moving forwardly in relation to thetubular body 115; As previously discussed in relation to thesample-admitting means 28, the enclosed counterbore 122 is initiallyfilled with a viscous fluid which, as it is discharged through thepassage 123 into the space 121, will regulate the speed of the rearwardtravel of the cylindrical body 124 as the sample-admitting means 100 areextended.

Accordingly, as far as has been described, it will be recognized that,in many respects, the sample-admitting means 100 are basically arrangedin the same manner as the sample-admitting means 29. One significantdistinction, however, is that, in its initial position shown in FIG. 6,the cylindrical body 124 and the O-rings 125 and 126 function as valvemeans blocking fluid communication (through the bore 129 and passage130) between the rear of the lateral housing bore 56 and the tubularextension 131. Furthermore, another significant difference between thesample-admitting means 29 and is provided by a cylindrical plug 136 thatis slidably disposed within a reduced bore 137 at the forward end of thesampling tube 101 and fluidly sealed therein, as by an O-ring 138, tofunction as valve means for preventing entrance of borehole fluids into'the sample-admitting means 100 so long as the sampling tube is retractedin relation to the outer tubular member 102. Although the plug 136 couldjust as well be mounted on the forward end of the tubular extension 131,it is preferred that the cylindrical plug be a separate member that isarranged to normally abut the transverse member 134 so as to not beshifted rearwardly by unbalanced pressure forces so long a the samplingtube 101 is retracted.

it will be appreciated, therefore, that with the sample-admitting means100 retracted as shown in H6. 6, the interior bore 112 of the outertubular member 102 (between the 0- rings 113 and is closed againstentrance of borehole fluids. Similarly, the valve means respectivelyincluding the 0- rings and 138 selectively close the interior spaces ofthe sampling tube 101 and cylindrical body 124. Thus, in contrast to thesample-admitting means 29, when the sample-admitting means 100 areemployed, borehole fluids cannot enter the formation-sampling apparatus20 so long as the sample-admitting means 100 are retracted.

Accordingly, turning now to FIG. 7, the sample-admitting means 100 aredepicted in a corresponding position as shown in FIG. 3 for thesample-admitting means 29. Since the operation of the tool 20 to thispoint will have been as previously explained, it is necessary only topoint out that the hydrostatic pressure of the borehole fluids has beenemployed to extend the piston 106 so as to sealingly engage the packingelement 103 against the mudcake layer 96 on the wall of the borehole 22.Once the piston 106 is stroked forwardly a sufficient distance to movethe flanged end 135 of the valve member 124 away from the rear wall ofthe housing bore 38, the hydro static pressure of the borehole fluidswill, of course, begin urging the forward plug or valve member 136, thetubular extension 131 and the cylindrical body 124 rearwardly inrelation to the still retracted sampling tube 101. Rearward movement ofthese members is, however, selectively retarded by the fluent substancethat is initially disposed in the counterbored annular space 122 aroundthe cylindrical body 124. Thus, in the same manner as previouslydescribed for the sample-admitting means 29, the plastic substanceinitially disposed in the counterbore 122 must be slowly exhaustedthrough the restricted passage 123 into the clearance space 121 as thecylindrical body 124 moves at a regulated speed to the rearwardpositions shown in FIGS. 7 and 8.

Rearward travel of the forward valve member 136 is operative to open thereduced entrance 137 of the sampling tube 101 before the O-ring 125closing the lateral passage in the cylindrical body 124 clears therearward end of the tubular body 115. Thus, with the sample-admittingmeans 100, only a minor momentarily-voided space, as at 139, isinitially opened for receiving any plug of the mudcake 96 and loosenedformation materials entering the sampling tube 101. As seen in FIG. 7,therefore, this mudcake plug will be disposed well behind the filteringscreen 132 within the progressively enlarging space 139 respectivelyformed ahead of the shoulder 127 of the retreating valve body 124 and,if it moves, behind the advancing piston 110 of the sampling tube 101 aswell. Then, after this initial quantity of mudcake enters the sample-admitting means 100, the passage 130 will open as the valve body 124continues moving toward its rearwardmost position to establishcommunication with the additional voided spaces in the rear of thehousing bore 56 and the open portion of the passage 43. The flow linevalve 45 is, of course, still closed at this point.

Accordingly, although the sample-admitting means 100 function in agenerally similar manner as the sample-admitting means 29, thesignificantly reduced volume of the initially voided space 139 (inrelation to the combined volume of the space 92 and bore 56) will allowthe sampling tube 101 to make at least a slight advancement into theformation 23 before the large volume of the housing bore is opened. Itis believed, therefore,that if the nose of the sampling tube 101 can befirst embedded into an unconsolidated formation before the passage 130is opened, there will be a correspondingly reduced chance that theborehole fluids will channel through the mudcake 96 and contiguousformation wall supporting the forward face of the pad 103. It will alsobe appreciated that since only the voided space 139 is initially opened,all of the mudcake plug will be drawn into this space and, since thereis no flow through the filtering screen, greatly minimize any coatingover the screen 132.

In some instances, however, it has been found of added benefit to fillthe passage 129 with a viscous fluid, such as grease or the like, beforethe apparatus is lowered into the borehole 22. When this is done, itwill be appreciated that upon opening of the forward valve member 136,there is no tendency at all for the mudcake plug to be drawn onto thescreen 132 since there is no pressure differential across the screenuntil the rearward valve means defined by the O-ring 125 and body 115open. Similarly, if this technique is carried one step further, by alsopre-filling the interior of the sampling tube 101 with a suitableliquid, opening of the forward valve meinber 136 will still furtherreduce the voided space 139 and require advancement of the sampling tubeto develop at least a major portion of this space. Thus, since thesampling tube 101 will be advanced sooner, it will be even moreresponsive to moving into the formation 23 as loosened materialstherefrom enter the sample admitting means 100. This more rapid responseof the sampling tube 101 will, therefore, further assure the retentionof an effective sealing engagement of the sealing member 103 with theborehole wall.

As seen in FIG. 8, once the flow line valve 45 is opened, the furtheroperation of the sample-admitting means 100 will be the same as that ofthe sample-admitting means 29. Similarly, retraction of thesample-admitting means 100 will be as previously described in relationto FIG. 5.

Referring again to FIG. 6, it will be noted that the nose of thesampling tube 101 projects forwardly of the spherical head 105 and isabout even with the forward face of the packing element 103 when thesample-admitting means 100 are retracted. Thus, when the piston 106initially advances to compress the elastomeric pad 103 into sealingengagement against the mudcake 96, the face of the sealing member willmove rearwardly in relation to the sampling tube 101 to leave the noseof the tube projecting slightly ahead. Accordingly, since the samplingtube 101 will still be seated against the tubular body 115 so long asthe valve body 136 is in the bore 138, the forward thrust of the piston106 will be operative to at least partially embed the nose of thesampling tube 101 into the mudcake 96.

As previously mentioned, however, it is preferred to make the samplingtube 101 relatively weak since it is not retracted once thesample-admitting means 100 are extended. Thus, to

reduce the axial load on the sampling tube 101 durir'ig the abovedescribed setting operation, a short rigid sleeve 140 is coaxiallymounted in the forward end of the spherical head 105 and arranged to beabout even with the nose of the sampling tube so long as the samplingtube is retracted. it will be appreciated, therefore, that although theengagement of the forward end of the sleeve 140 against the formationwall will reduce the axial loading on the sampling tube 101 during thesetting operation, when the test is subsequently finished the extendedsampling tube will still be readily bent or broken as the tool 20 isbeing moved from its sampling position.

Turning now to H6. 9, a third embodiment is shown of sample-admittingmeans 200 which may alternatively be employed in the apparatus 20 of thepresent invention.

Hereagain, the same reference numbers used in FIG. 2 have been retainedto designate the previously-described common elements.

In general, it will be appreciated that the sample-admitting means 200are somewhat similar to the sample-admitting means 100. Thus, in thesame or similar fashion, the sampleadmitting means 200 include a tubularsampling member 201 that is slidably arranged for axial movement in thelateral housing bore 56 and has its forward portion fluidly sealed bythe O-ring 57. An annular piston 202 is also sealingly arranged in thecoaxial bore and includes a forward extension 203 projecting through theO-ring 84 and connected, as at 204, to the forward end of the tubularmember 201. In the same manner as already described, a cylindrical valvemember 205 is operatively arranged for selective movement in the axialbore 206 of the tubular member 201. Hereagain, spaced 0- rings 207 and208 on the rear of the valve member 205 function as valve means forblocking communication through a central passage 209 therein so long asthe O-rings are operatively engaged within a tubular body 210 securedwithin the rear portion of the sampling tube 201. Similarly, a tubularforward extension 211 of the cylindrical valve member 205 is perforated,as at 212, and supports a filtering screen 213 and a forward plug 214adapted to be sealingly received within a reduced axial bore 215 that(in contrast to the sample-admitting means is formed in the nose of thetubular member 201. Inner and outer enclosed chambers 216 and 217connected by a passage 218 are operatively arranged between the tubularbody 210 and valve member 205 for regulating the rearward travel of thevalve member as a viscous material is displaced from the inner chamberinto the outer chamber.

An elastomeric packing element 219 is coaxially mounted on the forwardend of the tubular member 201 and operatively arranged to belongitudinally compressed in relation to the tubular member as thesample-admitting means 200 are advanced into sealing engagement with aborehole wall. in the preferred manner of accomplishing this, thepacking element 219 is symmetrically arranged in relation to the tubularmember 201 and includes a transverse forward portion 220 having acentral opening 221 carrying a tubular sealing member 222 coaxiallydisposed for movement over the tubular member 201 and a rearwardlydirected peripheral skirt portion 223. By securing the skirt portion 223of the packing element 219 to a rigid, transverse supporting plate 224secured to an intermediate portion of the sampling tube 201 and leavingthe forward transverse portion 220 free to move axially in relation tothe tubular member, it will be appreciated that as the wall-engagingforward face of the elastomeric member engages a borehole wall theelastomeric element will compress and move rearwardly in relation to thesampling tube.

Accordingly, as best seen in FIG. 10, upon extension of thesample-admitting means 200, once the sealing element 219 engages themudcake layer 96, the forwardly directed force developed by the piston202 will be effective to sealingly engage the forward face of thetransverse portion 220 on the borehole wall. Of particular significance,however, it will be recognized that a major portion of the force of thepiston 202 will be effective for driving the nose of the sampling tubeinto the mudcake layer 96 and, quite possibly, the formation 23 as well.Thus, as the sealing member 219 moves rearwardly in relation to thetubular member 201, the sampling tube will, in effect, be advancedforwardly in relation to the outer tubular member 222 carrying thetransverse portion 220 of the elastomeric member. it will also beappreciated that by providing one or more ports, as at 225, through thesupporting plate 224, once the face of the elastomeric element 219 issealingly engaged on a borehole wall the hydrostatic pressure of theborehole fluids acting on the rear face ofthe transverse portion 220will be effective to enhance the sealing engagement.

Thus, as seen in FIG. 10, as the sample-admitting means 200 are beingoperatively engaged with a borehole wall, the valve plug 214 willinitially be withdrawn from the forward reduced bore 215 in the samplingtube 201 to admit mudcake and any 'bore 56 and the formation 23.Hereagain, it will be understood that the flow line valve 45 is stillclosed. Thus, from this point on, it will be recognized that theoperation of the tool 20 will be as previously described.

As one advantage of the sample-admitting means 200 over thesample-admitting means 29 and 100, the sampling tube 201 is adapted forpositive retraction after a testing operation. Thus, the tubular member201 can be made of sufficient strength to withstand the substantialaxial loads necessary for positively driving it through the mudcake 96and, possibly, into an unconsolidated formation.

Those skilled in the art will appreciate that irrespective of whether awater cushion, as at 41, is or is not employed, when a fluid sample isbeing taken there will be a substantial pressure differential existingbetween the connate fluids entering the forward portion of thesample-admitting means 29, 100 or 200 and the enclosed sample chamber 38which is initially at atmospheric pressure. This extreme pressuredifferential must, of course, be accommodated in either instance. Thus,if the water cushion 41 and the other chamber 37 are employed, most ofthis pressure differential will be taken across the orifice 40 so thatonly a minimal pressure drop will occur in the sample-admitting means29, 100 or 200. On the other hand, if the water cushion 41 is notemployed in the tool 20, the pres sure drop will be primarilyaccommodated across the filtering screen 78 and the apertures 77 (andtheir corresponding elements in the sample-admitting means 100 and 200).If need be, additional flow restriction can be provided by arrangingsuitable orifices or the like (not shown) in either the passage 76 (or129 and 209) or flow line 43.

in any event, there are, of course, widely different types of formationsfrom which samples are to be taken. In those situations where theformations are fairly competent, it is not at all likely that theperformance of the sample-admitting means 29, 100 or 200 would beaffected by elimination of the water cushion 4]. On the other hand, thewater cushion 41 may assure a more reliable operation with thesample-admitting means 29, 100 or 200 where a particularly uncementedgranulated formation material is anticipated. The choice is, therefore,best determined by actual operating experience in each particular oilfield.

,Turning now to FIG. 11, an alternative arrangement is shown forincreasing the travel of the sample-admitting means 29, 100 or 200.Inasmuch as this arrangement is the same as shown in US. Pat. No.3,385,364, it is necessary only to state that the two coaxially-arrangedsuccessively extendible pistons 300 and 301 can be readily employed as asubstitute for the piston 79 of the sample-admitting means 29, thepiston 106' of the sample-admitting means 100, or the piston 202 of thesample-admitting means 200. Since the unique cooperationof the pistons300 and 301 is fully explained in the aforementioned patent, the detailsof their operation need not be described further.

Accordingly, it will be appreciated that the present invention hasprovided new and improved formation-sampling apparatus adapted forreliably establishing and maintaining fluid communication with varioustypes of borehole surfaces and formation materials. Thus, althoughchanges and modifications may be made in the principles of the inventionas set out in the claims, by limiting the entrance of mudcake and anyunconsolidated formation materials into the formation-samplingapparatus, greater assurance is had that satisfactory fluid samples willbe obtained.

lclaim:

l. Fluid-sampling apparatus adapted for obtaining samples of connatefluids from earth formations traversed by a well bore and comprising: asupport; sample-admitting means on said support and including inner andouter telescoped tubular members operatively arranged thereon formovement between retracted and extended positions; first means adaptedfor extending said outer member into engagement with an adjacent surfaceof a well bore; second means adapted for extending said inner memberinto engagement with a portion of such an adjacent well bore surface;and means operatively associated with said first and second means fordelaying extension of said inner member until after extension of saidouter member.

2. The fluid-sampling apparatus of claim 1 wherein said extensiondelaying means normally maintain said inner member retracted so long assaid outer member is retracted.

3. The fluid-sampling apparatus of claim 1 further including: packingmeans operatively mounted on saidouter member and adapted to be carriedthereby into sealing engagement around such'an adjacent well boresurface upon extension of said outer member.

4. The fluid-sampling apparatus of claim I further including: passagemeans operatively arranged within said inner member and adapted toconduct fluids entering said sampleadmitting means; filter meansoperatively arranged within said inner member and in fluid communicationwith said passage means for straining solid matter from such fluidsentering said passage means; and means defining a space within saidinner member and adapted for receiving such solid matter.

5. The fluid-sampling apparatus of claim 4 wherein said space is to therear of said filter means for separating such solid matter from saidfilter means.

6. The fluid-sampling apparatus of claim 4 further including: valvemeans operatively associated with said extensiondelaying means forclosing off said space until after extension of said outer member.

7. Fluid-sampling apparatus adapted for obtaining samples of connatefluids from earth formations traversed by a well fluent solid materials;sample-collecting means on said support including a first chamberadapted for receiving such connate fluids, and passage means arrangedbetween said first chamber and said tubular member for conducting suchconnate fluids passing through said filtering means into said firstchamber; means defining a second chamber in said tubular member adaptedfor receiving such fluent solid materials; and valve means normallyclosing said second chamber and adapted to be opened in response toextension of said tubular member for admitting such fluent solids intosaid second chamber.'

8. The fluid-sampling apparatus of claim 7 further including: meansoperatively associated with said tubular member and said valve means fordelaying opening of said valve means until after extension of saidtubular member.

9. The fluid-sampling apparatus of claim 7 further includ-. ing:selectively operable means on said support adapted for extending saidtubular member; and means operatively associated with said tubularmember and said valve means for delaying opening of said valve meansuntil after extension of 1 said tubular member by operation of saidselectively operable means.

10. The fluid-sampling apparatus of claim 7 further including: packingmeans operatively mounted on said tubular member and adapted to becarried thereby'into sealing engagement around such an adjacent wellbore surface upon extension of said tubular member.

11. Fluid-sampling apparatus adapted for obtaining samples I of connatefluids from earth formations traversed by a well bore and comprising: asupport; sample-admitting means on said support including a tubularsampling member having an.

internal bore and adapted for extension from said support to place theforward end of said sampling member into fluid communication with a wellbore surface adjacent to earth formations; filtering means in saidinternal bore adapted for passing such connate fluids and retaining suchfluent solid materials carried into said internal bore by such fluids;sample-collecting means on said support including a first chamberadapted for receiving such connate fluids, and passage means arrangedbetween said first chamber and said internal bore for conducting suchconnate fluids passing through said filtering means into said firstchamber; means defining a second chamber in said internal bore adaptedfor receiving such retained solid materials; valve means normallyclosing said forward end of said sampling member; and means operativelyassociated with said sampling member and said valve means for delayingopening of said valve means until said sampling member is beingextended.

12. Fluid-sampling apparatus adapted for obtaining samples of connatefluids from earth formations traversed by a well bore and comprising: asupport; sample-admitting means on said support including a tubularmember adapted for extension from said support to place the forward endof said tubular member into fluid communication with a well bore surfaceadjacent to earth formations and including fluent solid materials, and atubular sampling member having an internal bore and telescopicallyarranged within said tubular member for extension through said forwardend thereof; filtering means in said internal bore adapted for passingsuch connate fluids and retaining such fluent solid materials;sample-collecting means on said support including a first chamberadapted for receiving such connate fluids, and passage means arrangedbetween said first chamber and said internal bore for conducting suchconnate fluids passing through said filtering means into said firstchamber; means defining a second chamber in said internal bore to therear of said filtering means and adapted for receiving such fluent solidmaterials; and valve means normally closing said second chamber andopened in response to extension of said tubular member for admittingsuch fluids and fluent solids into said second chamber.

13. The fluid-sampling apparatus of claim 12 further including: meansoperatively associated with said tubular member and said valve means fordelaying opening of said valve means until after extension of saidtubular member.

14. The fluid-sampling apparatus ofclaim 12 further including: meansresponsive to admission of such fluids and fluent solids into saidsecond chamber for extending said sampling member through such forwardend of said tubular member; and means operatively associated with saidtubular member and said valve means for retarding opening of said valvemeans until after extension of said tubular member to delay extension ofsaid sampling member.

15. Fluid-sampling apparatus adapted for obtaining samples of connatefluids from earth formations traversed by a well bore and comprising: asupport; sample-admitting means on said support including a tubularmember adapted for extension from said support to place the forward endof said tubular member into fluid communication with a well bore surfaceadjacent to earth formations and including fluent solid materials, and atubular sampling member having an internal bore and telescopicallyarranged within said tubular member for extension through said forwardend thereof; filtering meansjn said internal bore adapted for passingsuch connate fluids and restraining such fluent solid materials;sample-collectingmeans on said support including a first chamber adaptedfor receiving such connate fluids, and passage means arranged betweensaid first chamber and said internal bore for conducti'ng such connatefluids passing through said filtering means into said first chamber;means defining a second chamber in said internal bore to the rear ofsaid filtering means and adapted for receiving such fluent solidmaterials; and valve means normally closing the forward end of saidsampling member to close said second chamber and operatively arranged tobe opened in response to extension of said tubular member for admittingsuch fluids and fluent solids into said second chamber.

16. The fluid-sampling apparatus of claim 15 further including: meansoperatively associated with said tubular member and said valve means fordelaying opening of said valve means until after extension of saidtubular member.

17. The fluid-sampling apparatus of claim 15 further including: meansresponsive to admission of such fluids and fluent solids into saidsecond chamber for extending said sampling member through such forwardend of said tubular member; and means operatively associated with saidtubular member and said valve means for retarding opening of said valvemeans until after extension of said tubular member to delay extension ofsaid sampling member.

18. Fluid-sampling apparatus adapted for obtaining samples of connatefluids from earth formations traversed by a well bore and comprising: asupport; sample-admitting means on said support including a tubularmember having an internal bore and adapted for extension from saidsupport to place the forward end of said tubular member into fluidcommunication with a well bore surface adjacent to earth formations andincluding fluent solid materials; filtering means in said internal boreadapted for passing such connate fluids and retaining such fluent solidmaterials; sample-collecting means on said support including a firstchamber adapted for receiving such connate fluids, and passage meansarranged between said first chamber and said internal bore forconducting such connate fluids passing through said filtering means intosaid first chamber; means defining a second chamber in said internalbore adapted for receiving such fluent solid materials; and valve meansnormally closing said forward end of said tubular member to enclose saidsecond chamber and operatively arranged to be opened in response toextension of said tubular member for admitting such fluids and fluentsolids into said second chamber.

19. The fluid-sampling apparatus of claim 18 further including: meansoperatively associated with said tubular member and said valve means fordelaying opening of said valve means until after extension of saidtubular member.

20. The fluid-sampling apparatus of claim 18 further including: secondvalve means normally closing said passage means and operatively arrangedto be opened in response to extension of said tubular member foradmitting such fluids into said first chamber; and means operativelyassociated with said tubular member and said first and said second valvemeans for retarding opening thereof until after extension of saidtubular member.

21. The fluid-sampling apparatus of claim 20 wherein said first valvemeans are adapted to be opened before said second valve means areopened.

22. Fluid-sampling apparatus adapted for obtaining samples of connatefluids from earth formations traversed by a well bore and comprising: asupport having an open bore therein; a tubular member operativelyarranged for axial movement in said bore between a retracted positionand an extended position and having a forward end adapted for engagementwith a wall of a well bore upon movement to said extended position;packing means operatively mounted on said forward end of said tubularmember and adapted to be carried thereby into sealing engagement withsuch a well bore wall for isolating said forward end of said tubularmember from well bore fluids; a movable body having a passage extendingbetween forward and rearward portions thereof coaxially mounted withinsaid tubular member for axial movement therein between first and secondpositions; means selectively operable for moving said tubular memberfrom its said retracted position to its said extended position;filtering means on said forward portion of said body in communicationwith said passage and adapted for straining fluent solid materials fromsuch connate fluids admitted into the annular space between said bodyand said tubular member and passing into said passage; valve meansoperatively arranged between said forward portion of said body and saidtubular member for closing fluid communication between said.forward endof said tubular member and said annular space so long as said body is inone of its said positions; and means normally positioning said body inits said one position and responsive to movement of said tubular membertoward its said extended position for shifting said body to the other ofits said positions to open said valve means.

23. The fluid-sampling apparatus of claim 22 further including: meansoperatively associated with said body for delaying shifting of said bodyto its said other position.

24. The fluid-sampling apparatus of claim 22 further including:sample-collecting means on said support including a chamber adapted forreceiving such connate fluids, and passage means operatively coupledbetween said chamber and said passage.

25 The fluid-sampling apparatus of claim 22 further including: secondvalve means operatively arranged between said rearward portion of saidbody and said tubular member for closing fluid communication throughsaid passage so long as said body is in its said one position.

26. The fluid-sampling apparatus of claim 25 further including: meansoperatively associated with said body for delaying shifting of said bodyto its said other position.

27. The fluid-sampling apparatus of claim 26 wherein said second valvemeans are adapted to remain closed until after said first-mentionedvalve means are opened.

28. Fluid-sampling apparatus adapted for obtaining samples of connatefluids from earth formations traversed by a well bore and comprising: asupport having an open bore therein; sample-admitting means on saidsupport including a tubular member operatively arranged for axialmovement in said bore between a retracted position and an extendedposition and having a forward end adapted for engagement with a wall ofa well bore upon movement to said extended position, and a tubularsampling member having an internal bore and telescopically arrangedwithin said tubular member for extension through said forward endthereof; packing means operatively mounted on said forward end of saidtubular member and adapted to be carried thereby into sealing engagementwith such a well bore wall for isolating said forward end of saidtubular member from well bore fluids; a movable body having a passageextending between forward and rearward portions thereof coaxiallymounted within said tubular members for axial movement therein betweenfirst and second positions; means selectively operable for moving saidtubular member from its said retracted position to its said extendedposition; filtering means on said forward portion of said body incommunication with said passage and adapted for straining fluent solidmaterials from such connate fluids admitted into the annular spacebetween said body and said sampling member and passing into saidpassage; valve means operatively arranged between said forward portionof said body and said sampling member for closing fluid communicationbetween the forward end of said sampling member and said annular spacetherebehind so long as said body is in one of its said positions; andmeans normally positioning said body in its said one position andresponsive to movement of said tubular member toward its said extendedposition for shifting said body to the other of its said positions toopen said valve means.

29. The fluid-sampling apparatus of claim 28 further including: meansoperatively associated with said body for delaying shifting of said bodyto its said other position.

30. The fluid-sampling apparatus of claim 28 further including:sample-collecting means on said support including a chamber adapted forreceiving such connate fluids, and passage means operatively coupledbetween said chamber and said passage.

31. The fluid-sampling apparatus of claim 28 further including: secondvalve means operatively arranged between said rearward portion of saidbody and said tubular member for closing fluid communication throughsaid passage so long as said body is in its said one position.

32. The fluid-sampling apparatus of claim 31 further including: meansoperatively associated with said body for delaying shifting of said bodyto its said other position.

33. The fluid-stamping apparatus of claim 32 wherein said second valvemeans are adapted to remain closed until after said first mentionedvalve means are opened.

